limiter.acquire(Integer.MAX_VALUE / 4);
    limiter.acquire(Integer.MAX_VALUE / 2);
    limiter.acquire(Integer.MAX_VALUE);
    assertEvents("R0.00", "R0.00", "R0.00"); // no wait, infinite rate!

    limiter.setRate(2.0);
    limiter.acquire();
    limiter.acquire();
    limiter.acquire();
    limiter.acquire();
    limiter.acquire();
    assertEvents(

    limiter.acquire(Integer.MAX_VALUE / 4);
    limiter.acquire(Integer.MAX_VALUE / 2);
    limiter.acquire(Integer.MAX_VALUE);
    assertEvents("R0.00", "R0.00", "R0.00"); // no wait, infinite rate!

    limiter.setRate(2.0);
    limiter.acquire();
    limiter.acquire();
    limiter.acquire();
    limiter.acquire();
    limiter.acquire();
    assertEvents(

   */
  @CanIgnoreReturnValue
  public double acquire() {
    return acquire(1);
  }

  /**
   * Acquires the given number of permits from this {@code RateLimiter}, blocking until the request
   * can be granted. Tells the amount of time slept, if any.
   *
   * @param permits the number of permits to acquire
   * @return time spent sleeping to enforce rate, in seconds; 0.0 if not rate-limited

 *
 * <p>Deadlocks can arise when locks are acquired in an order that forms a cycle. In a simple
 * example involving two locks and two threads, deadlock occurs when one thread acquires Lock A, and
 * then Lock B, while another thread acquires Lock B, and then Lock A:
 *
 * <pre>
 * Thread1: acquire(LockA) --X acquire(LockB)
 * Thread2: acquire(LockB) --X acquire(LockA)
 * </pre>
 *

     * <p>To avoid races between threads doing release and acquire, we transition to the final state
     * in two steps. One thread will successfully CAS from RUNNING to COMPLETING, that thread will
     * then set the result of the computation, and only then transition to COMPLETED, CANCELLED, or
     * INTERRUPTED.
     *
     * <p>We don't use the integer argument passed between acquire methods so we pass around a -1
     * everywhere.
     */

     * <p>To avoid races between threads doing release and acquire, we transition to the final state
     * in two steps. One thread will successfully CAS from RUNNING to COMPLETING, that thread will
     * then set the result of the computation, and only then transition to COMPLETED, CANCELLED, or
     * INTERRUPTED.
     *
     * <p>We don't use the integer argument passed between acquire methods so we pass around a -1
     * everywhere.
     */

the header line. This behavior can be disabled with `GODEBUG=tracebacklabels=0`
(added in [Go 1.26](/doc/godebug#go-126)). This opt-out is expected to be
kept indefinitely in case goroutine labels acquire sensitive information that

    // Put a floor on the keep alive duration, otherwise cleanup will spin loop.
    require(keepAliveDuration > 0L) { "keepAliveDuration <= 0: $keepAliveDuration" }
  }

  fun idleConnectionCount(): Int =
    connections.count {
      it.withLock { it.calls.isEmpty() }
    }

  fun connectionCount(): Int = connections.size

  /**
   * Attempts to acquire a recycled connection to [address] for [call]. Returns the connection if it

    //                                                                    ================

    /**
     * Attempts to acquire a distributed lock for the specified operation.
     *
     * @param operationName the operation name used as the lock document ID.
     * @return {@code true} if the lock was acquired.
     */
    public boolean tryStartOperation(final String operationName) {
        return tryStartOperation(operationName, null);

* Nginx
* HAProxy

## Let's Encrypt { #lets-encrypt }

Before Let's Encrypt, these **HTTPS certificates** were sold by trusted third parties.

The process to acquire one of these certificates used to be cumbersome, require quite some paperwork and the certificates were quite expensive.

But then **[Let's Encrypt](https://letsencrypt.org/)** was created.